Students working with the Toward High-School Biology curriculum. [Credit:
AAAS]

AAAS research, presented at a recent meeting of the National Association for Research in Science Teaching (NARST), has shown that students made significant advances in understanding key chemistry and biology ideas by learning them together.

A new eighth-grade curriculum unit—under development by Project 2061, the association’s science-education reform initiative, in collaboration with the Colorado-based Biological Sciences Curriculum Study (BSCS) group—connects fundamental chemistry and biology concepts to better prepare students for biology in high school and college, where reports such as AAAS’s Vision and Change in Undergraduate Biology Education have called for a more cross-disciplinary approach.

After pilot-testing the curriculum, 677 eighth-graders from four states “made statistically significant gains in their understanding of the targeted ideas and held fewer misconceptions,” said Jo Ellen Roseman, director of Project 2061.

The students’ understanding of chemical reactions, conservation of mass, and biological growth were tested both before and after they had completed the new unit. Before completing the new chemistry unit, 42 percent of students who took part in pilot tests seemed to incorrectly believe that all of the food that an animal eats becomes waste and, therefore, is not available for building the body structures needed for growth. After completing the curriculum, only 13 percent of the students still had this incorrect idea, said Cari Herrmann Abell, a senior research associate on the Project 2061 team.

Traditionally, Roseman explained, students have been taught biology before chemistry and in different classes, often in different grades. Yet, as the National Research Council has reported: “Much of modern biology has become increasingly chemical in character.” Too many U.S. middle-school students are struggling to learn fundamental concepts that are essential for more advanced studies of life, Roseman said. The new curriculum unit is being developed to reflect the National Research Council’s latest recommendations, set forth in A Framework for K-12 Science Education, which emphasize the importance of mastering core scientific ideas and practices, such as modeling and constructing explanations, across the disciplines.

To help students make sense of ideas about where the new “stuff” needed for biological growth comes from, for example, students in pilot test classrooms in Colorado, Maryland, Boston, and Washington, D.C. first observed the formation of new substances in simple chemical reactions they could model with LEGO® blocks. Then they observed the “growth” of nylon thread and modeled the underlying polymerization reaction. In a later lesson, students learned that animals’ bodies and the foods they eat are composed mostly of protein polymers. Then they modeled the chemical reaction that breaks down protein polymers into amino acids, and they learned that carbon atoms from amino acids become a part of animals’ bodies. Finally, the students created ball-and-stick models to illustrate the formation of protein polymers. A similar sequence of lessons helped them understand the formation of carbohydrate polymers for plant growth.

The research team also reported on their work with eight teachers who pilot-tested classroom support materials related to the new curriculum unit. In particular, the researchers assessed teachers’ knowledge of four key areas—chemical reactions, the conservation of mass, the flow of matter in living systems, and plant growth—as well as their understanding of student misconceptions and strategies for changing those ideas. “Teachers made gains over time in most of the knowledge areas and across most of the contexts,” reported Jean Flanagan, a research associate on the Project 2061 team. The results helped the team further refine their teacher support materials.

The new unit, Toward High-School Biology: Understanding Growth in Living Things is being developed with a grant from the U.S. Department of Education’s Institute of Education Sciences. AAAS researchers and their BSCS colleagues are now completing a third revision of the materials, based on data from pilot tests during the program’s second year. Next, the group will complete a randomized trial with six teachers to further assess the unit’s promise as compared with conventional curriculum.
Some small molecules (monomers), often containing carbon atoms arranged in chains or rings, can link together during chemical reactions to form large molecules (polymers) and water molecules. Monomers usually have groups of atoms at two places on the molecule that are important for linking many monomers together.

In plants, glucose monomers can react to form cellulose polymers and water. The cellulose polymers are used to build body structures during growth and repair.
The process by which proteins from food become part of animals’ body structures involves chemical reactions in which the proteins from food are broken down into amino acid monomers, and these monomers are used to build different protein polymers that make up body structures.

Example science ideas targeted for the Year 3 Towards High School Biology Unit [Credit: AAAS]